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Mount Cleveland (Alaska)
Encyclopedia
Mount Cleveland is a nearly symmetrical stratovolcano
on the western end of Chuginadak Island
, a remote landmass in the Aleutian Islands of Alaska. Cleveland is 1730 m (5,676 ft) high, and one of the most active of the 75 or more volcanoes in the larger Aleutian Arc
. Aleutian natives named the island after their fire goddess, Chuginadak, who they believed inhabited the volcano. In 1894 a team from the U.S. Coast and Geodetic Survey visited the island and gave Mount Cleveland its current name, after then-president Grover Cleveland
.
One of the most active volcanoes in the Aleutian Arc, Cleveland has erupted at least 21 times in the last 230 years. A VEI
3 eruption in 1944 produced the arc's only direct volcanic fatality. Most recently Mount Cleveland has erupted three times in 2009, twice in 2010, and once in 2011. The volcano's remoteness limits opportunities for its study, and the Alaska Volcano Observatory
relies heavily on satellites for monitoring. The volcano is primarily hazardous to aircraft; many of the flights over the north Pacific approach the vicinity of the volcano, and volcanic ash
released from eruptions can damage sensitive electronic equipment and sensors.
, a long volcanic chain extending off the coast of Alaska. Containing over 75 volcanoes, this volcanic arc
occurs above the subduction zone where the Pacific Plate
plunges under the North American plate
. As the plate moves deeper into the earth, the increasing pressure results in the loss of volatiles
, certain elements and compounds with low boiling points
, from various hydrous
mineral
s. One of these compounds is water; its addition to the mantle wedge
formed between the subducting and overriding plates lowers the melting point enough to allow magma to form. The melted material then rises to the surface and forms a volcano—in this case, the Aleutian Arc.
name for Mount Cleveland is Chuginadak (the name currently given to the island as a whole), referring to the Aleut fire goddess, thought to reside in the volcano. The volcano's name is a reference to its constant activity, and shows that it was likely highly active even in the distant past. Aleut oral tradition states that, at one time, the western and eastern halves of Chuginadak were separate islands, and that the isthmus joining them was created by volcanic activity sometime in prehistory. The "Islands of Four Mountains" name, the geographic group name for Cleveland and its neighbors, was given to the islands by Russian cartographers in the 19th century. Its current name, Mount Cleveland, was given to it by a U.S. Coast and Geodetic Survey expedition in 1894, when it was originally observed by the USS Concord; like the other volcanoes in the Four Islands group, Mount Cleveland was named after prominent American politicians at the time, Cleveland having been named after then-president Grover Cleveland
.
stratovolcano
in the Islands of Four Mountains
, a volcanic group in the Aleutian Arc
. Like all stratovolcanoes, Mount Cleveland grew as explosive eruption
s, effusive eruption
s, and lahar
s built it layer by layer into a concave-up shape. It lies southeast of Mount Carlisle
and northeast of Herbert Island
. Mount Cleveland forms the western half of Chuginadak Island
, a broad and uneven bell-shaped landmass, and is the highest of the four volcanic islands. The island is completely uninhabited; the nearest settlement is Nikolski
on Umnak Island, about 75 km (47 mi) eastward.
Mount Cleveland is 8–8.5 km (5–5.3 mi) wide at its base and roughly 29 km³ (7 cu mi) in volume. The volcano's slope increases markedly with height, from 19° at its lower flanks to 35° near its summit. Like many other Aleutian volcanoes, Cleveland's flanks are especially rough up to 300 m (984 ft), covered by multiple overlapping lava flows and debris fans that form an apron around the mountain. Lava flows are always built on top of debris flows as a result of the snow melt caused by the emission of heat just before an eruption. The flows are generally short, under 1 km (0.621372736649807 mi), and thin, less than 10 m (33 ft) thick, and are somewhat vegetated. Although Mount Cleveland is the tallest mountain in the group, it is rarely completely snowed in because of its constant activity disrupts snowfall. A lack of extant erosion shows that Mount Cleveland is likely a Holocene
volcano, forming within the last 10,000 years. All known events have occurred at Mount Cleveland's summit vent, but there are at least five small andesite
to dacite
volcanic domes on the lower flanks. The volcano has no caldera
.
The eastern half of Chuginadak, to which Mount Cleveland is connected by a narrow isthmus
, consists of several low-lying volcanic cone
s and two prominent peaks that have been heavily eroded, partly by glaciers. Known as the Tana volcanic complex, the two features measure 1170 m (3,839 ft) and 1093 m (3,586 ft) in elevation. A sample of rhyolite
has been recovered from Concord Point, the easternmost point on the island.
Eruptions from Mount Cleveland are generally vulcanian
and strombolian
in nature, characterized by short explosive
ash clouds
sometimes accompanied by a'a flows, lava fountain
s, pyroclastic flow
s, ash
and steam
emissions, lava dome
growth, and the ejection of breadcrust bombs. Hot springs were reportedly found on the volcano in the 1800s, and persistent fumarolic activity
was observed in the 1980s and 1990s. Mount Cleveland is a site of persistent steam emissions and thermal anomalies that represent constant background activity.
Little is known about Cleveland's early eruptive history as its remoteness makes it a difficult area to investigate, and discrepancies in names have caused confusion between events there and those on nearby Carlisle
. Even today, not all possible event are confirmed as eruptions by the Alaska Volcano Observatory
, and many are listed as "possible." In observed history, Mount Cleveland may have first erupted in 1744; the first confirmed eruption occurred in 1828. The volcano erupted again in 1836 (possibly), 1893, 1897 (possibly), 1929 (possibly), 1932, and 1938 (possibly).
The first notable eruption from Mount Cleveland was a Volcanic Explosivity Index
(VEI) 3 Vulcanian eruption
that occurred between June 10 and June 13, 1944. Lava flows extended 5 kilometres (3 mi) from the summit, and an ash plume 6000 m (19,685 ft) high was produced. Large boulders were reportedly ejected and carried out to sea by eruptive force. The eruption had the distinction of being the only confirmed direct volcanic fatality in Alaska; a small detachment from the Eleventh Air Force
was stationed on the volcano at the time, and one Sergeant Purchase left his post early in the eruption to take a walk and never returned, probably killed by mudslides. At approximately 10:20, a boat sent to search for Purchase witnessed the end of the eruption. The island was abandoned for the remainder of the war.
Mount Cleveland erupted more recently in 1951, 1953, 1954 (possibly), 1975 (possibly), 1984 through 1987, 1989, 1994, and 1997. The volcano has received more focused attention in recent times due to its increased activity: it erupted in 2001, 2005, three times in 2006, 2007, three times in 2009, and twice in 2010. Of these, the most significant eruption was the 2001 eruption, which produced a 12 km (7 mi) high ash plume. This plume dispersed 120 to 150 km (74.6 to 93.2 mi) across Alaska, an unusual distance that allowed detailed satellite observations to be made. Nikolski and the surrounding region was the site of several hours of ashfall, represented in satellite imagery as areas of discolored snow. This eruption significantly disrupted air traffic in the area. The volcano has erupted at least 21 times in the last 230 years, with the most recent beginning on May 30 2010 and ending in late May or early June.
Today, the Alaska Volcano Observatory
monitors activity at Mount Cleveland using satellite imagery. Cloud cover often obscures the volcano, which makes many events difficult to follow. In addition, the low resolution of the satellite imagery allows minor events, which do not make an impression on the satellite picture, to pass unnoticed. There are no seismic or geophysical instruments on the mountain (the nearest are in Nikolski), and some eruptions are first observed by pilots flying over the volcano. A field study was conducted in late 2001, and an automatic system based on thermal anomalies was implemented following eruptive events in 2005. In recent years the Alaska Volcano Observatory has made an effort to expand volcanic coverage westward along the Aleutian Arc.
The biggest threat posed by an eruption from Mount Cleveland is its ash plume, which can damage sensitive electronic equipment on overflying planes. Many aircraft traveling over the North Pacific and over the Arctic come within the vicinity of such a plume; the only way to avoid damage is to reroute the flight, which delays arrival time and adds $5,500 to $6,000 in extra fuel costs. Cleveland has therefore been assessed by the United States Geological Survey
as a volcano with "[a] high aviation threat score and no real-time ground based monitoring at the present time".
The current activity is not generating an ash plume, and the surrounding land is uninhabited, so the eruption is unlikely to affect anyone. The lava dome is currently limited to the volcanic crater, but this volcano's history suggests it could produce a small flow or even an explosion that would push ash up to flight levels for a short time.
Stratovolcano
A stratovolcano, also known as a composite volcano, is a tall, conical volcano built up by many layers of hardened lava, tephra, pumice, and volcanic ash. Unlike shield volcanoes, stratovolcanoes are characterized by a steep profile and periodic, explosive eruptions...
on the western end of Chuginadak Island
Chuginadak Island
Chuginadak Island is the largest island in the Islands of Four Mountains subgroup of the Aleutian archipelago. Chuginadak is an Aleutian name published by Captain Tebenkov in an 1852 map...
, a remote landmass in the Aleutian Islands of Alaska. Cleveland is 1730 m (5,676 ft) high, and one of the most active of the 75 or more volcanoes in the larger Aleutian Arc
Aleutian Arc
The Aleutian Arc is a large volcanic arc in the U.S. state of Alaska. It consists of a number of active and dormant volcanoes that have formed as a result of subduction along the Aleutian Trench...
. Aleutian natives named the island after their fire goddess, Chuginadak, who they believed inhabited the volcano. In 1894 a team from the U.S. Coast and Geodetic Survey visited the island and gave Mount Cleveland its current name, after then-president Grover Cleveland
Grover Cleveland
Stephen Grover Cleveland was the 22nd and 24th president of the United States. Cleveland is the only president to serve two non-consecutive terms and therefore is the only individual to be counted twice in the numbering of the presidents...
.
One of the most active volcanoes in the Aleutian Arc, Cleveland has erupted at least 21 times in the last 230 years. A VEI
Volcanic Explosivity Index
The Volcanic Explosivity Index was devised by Chris Newhall of the U.S. Geological Survey and Stephen Self at the University of Hawaii in 1982 to provide a relative measure of the explosiveness of volcanic eruptions....
3 eruption in 1944 produced the arc's only direct volcanic fatality. Most recently Mount Cleveland has erupted three times in 2009, twice in 2010, and once in 2011. The volcano's remoteness limits opportunities for its study, and the Alaska Volcano Observatory
Alaska Volcano Observatory
The Alaska Volcano Observatory is a joint program of the United States Geological Survey, the Geophysical Institute of the University of Alaska Fairbanks, and the State of Alaska Division of Geological and Geophysical Surveys...
relies heavily on satellites for monitoring. The volcano is primarily hazardous to aircraft; many of the flights over the north Pacific approach the vicinity of the volcano, and volcanic ash
Volcanic ash
Volcanic ash consists of small tephra, which are bits of pulverized rock and glass created by volcanic eruptions, less than in diameter. There are three mechanisms of volcanic ash formation: gas release under decompression causing magmatic eruptions; thermal contraction from chilling on contact...
released from eruptions can damage sensitive electronic equipment and sensors.
Geological setting
Mount Cleveland is located 490 km (304 mi) from the western end of the Aleutian ArcAleutian Arc
The Aleutian Arc is a large volcanic arc in the U.S. state of Alaska. It consists of a number of active and dormant volcanoes that have formed as a result of subduction along the Aleutian Trench...
, a long volcanic chain extending off the coast of Alaska. Containing over 75 volcanoes, this volcanic arc
Volcanic arc
A volcanic arc is a chain of volcanoes positioned in an arc shape as seen from above. Offshore volcanoes form islands, resulting in a volcanic island arc. Generally they result from the subduction of an oceanic tectonic plate under another tectonic plate, and often parallel an oceanic trench...
occurs above the subduction zone where the Pacific Plate
Pacific Plate
The Pacific Plate is an oceanic tectonic plate that lies beneath the Pacific Ocean. At 103 million square kilometres, it is the largest tectonic plate....
plunges under the North American plate
North American Plate
The North American Plate is a tectonic plate covering most of North America, Greenland, Cuba, Bahamas, and parts of Siberia, Japan and Iceland. It extends eastward to the Mid-Atlantic Ridge and westward to the Chersky Range in eastern Siberia. The plate includes both continental and oceanic crust...
. As the plate moves deeper into the earth, the increasing pressure results in the loss of volatiles
Volatiles
In planetary science, volatiles are that group of chemical elements and chemical compounds with low boiling points that are associated with a planet's or moon's crust and/or atmosphere. Examples include nitrogen, water, carbon dioxide, ammonia, hydrogen, and methane, all compounds of C, H, O...
, certain elements and compounds with low boiling points
Volatility (chemistry)
In chemistry and physics, volatility is the tendency of a substance to vaporize. Volatility is directly related to a substance's vapor pressure. At a given temperature, a substance with higher vapor pressure vaporizes more readily than a substance with a lower vapor pressure.The term is primarily...
, from various hydrous
Hydrate
Hydrate is a term used in inorganic chemistry and organic chemistry to indicate that a substance contains water. The chemical state of the water varies widely between hydrates, some of which were so labeled before their chemical structure was understood....
mineral
Mineral
A mineral is a naturally occurring solid chemical substance formed through biogeochemical processes, having characteristic chemical composition, highly ordered atomic structure, and specific physical properties. By comparison, a rock is an aggregate of minerals and/or mineraloids and does not...
s. One of these compounds is water; its addition to the mantle wedge
Mantle wedge
A mantle wedge is a zone of mantle, triangular in cross–section, that lies between subducting and overriding tectonic plates. Flow inside the wedge is aligned with plate motions. Flux melting of material within wedge due to the release of volatiles from the underlying subducting slab results in...
formed between the subducting and overriding plates lowers the melting point enough to allow magma to form. The melted material then rises to the surface and forms a volcano—in this case, the Aleutian Arc.
Etymology
The native AleutAleut language
Aleut is a language of the Eskimo–Aleut language family. It is the heritage language of the Aleut people living in the Aleutian Islands, Pribilof Islands, and Commander Islands. As of 2007 there were about 150 speakers of Aleut .- Dialects :Aleut is alone with the Eskimo languages in the...
name for Mount Cleveland is Chuginadak (the name currently given to the island as a whole), referring to the Aleut fire goddess, thought to reside in the volcano. The volcano's name is a reference to its constant activity, and shows that it was likely highly active even in the distant past. Aleut oral tradition states that, at one time, the western and eastern halves of Chuginadak were separate islands, and that the isthmus joining them was created by volcanic activity sometime in prehistory. The "Islands of Four Mountains" name, the geographic group name for Cleveland and its neighbors, was given to the islands by Russian cartographers in the 19th century. Its current name, Mount Cleveland, was given to it by a U.S. Coast and Geodetic Survey expedition in 1894, when it was originally observed by the USS Concord; like the other volcanoes in the Four Islands group, Mount Cleveland was named after prominent American politicians at the time, Cleveland having been named after then-president Grover Cleveland
Grover Cleveland
Stephen Grover Cleveland was the 22nd and 24th president of the United States. Cleveland is the only president to serve two non-consecutive terms and therefore is the only individual to be counted twice in the numbering of the presidents...
.
Geography and structure
Mount Cleveland is an almost symmetrical andesiteAndesite
Andesite is an extrusive igneous, volcanic rock, of intermediate composition, with aphanitic to porphyritic texture. In a general sense, it is the intermediate type between basalt and dacite. The mineral assemblage is typically dominated by plagioclase plus pyroxene and/or hornblende. Magnetite,...
stratovolcano
Stratovolcano
A stratovolcano, also known as a composite volcano, is a tall, conical volcano built up by many layers of hardened lava, tephra, pumice, and volcanic ash. Unlike shield volcanoes, stratovolcanoes are characterized by a steep profile and periodic, explosive eruptions...
in the Islands of Four Mountains
Islands of Four Mountains
Islands of Four Mountains is an island grouping of the Aleutian Islands in Alaska, United States. The chain includes, from west to east, Amukta, Chagulak, Yunaska, Herbert, Carlisle, Chuginadak, Uliaga, and Kagamil Islands. This island chain is located between Amukta Pass and the Andreanof Islands...
, a volcanic group in the Aleutian Arc
Aleutian Arc
The Aleutian Arc is a large volcanic arc in the U.S. state of Alaska. It consists of a number of active and dormant volcanoes that have formed as a result of subduction along the Aleutian Trench...
. Like all stratovolcanoes, Mount Cleveland grew as explosive eruption
Explosive eruption
An explosive eruption is a volcanic term to describe a violent, explosive type of eruption. Mount St. Helens in 1980 was an example. Such an eruption is driven by gas accumulating under great pressure. Driven by hot rising magma, it interacts with ground water until the pressure increases to the...
s, effusive eruption
Effusive eruption
An effusive eruption is a volcanic eruption characterized by the outpouring of lava onto the ground...
s, and lahar
Lahar
A lahar is a type of mudflow or debris flow composed of a slurry of pyroclastic material, rocky debris, and water. The material flows down from a volcano, typically along a river valley. The term is a shortened version of "berlahar" which originated in the Javanese language of...
s built it layer by layer into a concave-up shape. It lies southeast of Mount Carlisle
Mount Carlisle
Mount Carlisle is a stratovolcano in Alaska which forms part of the 5 mile wide Carlisle Island, one of the Islands of Four Mountains which, in turn, form part of the central Aleutian Islands....
and northeast of Herbert Island
Herbert Island
Herbert Island is an island in the Islands of Four Mountains subgroup of the Aleutian archipelago. It is from Chuginadak Island, separated by the Chuginadak Pass...
. Mount Cleveland forms the western half of Chuginadak Island
Chuginadak Island
Chuginadak Island is the largest island in the Islands of Four Mountains subgroup of the Aleutian archipelago. Chuginadak is an Aleutian name published by Captain Tebenkov in an 1852 map...
, a broad and uneven bell-shaped landmass, and is the highest of the four volcanic islands. The island is completely uninhabited; the nearest settlement is Nikolski
Nikolski, Alaska
Nikolski is a census-designated place on Umnak Island in Aleutians West Census Area, Alaska, United States. The population was 39 at the 2000 census.-Geography:Nikolski is located at .According to the U.S...
on Umnak Island, about 75 km (47 mi) eastward.
Mount Cleveland is 8–8.5 km (5–5.3 mi) wide at its base and roughly 29 km³ (7 cu mi) in volume. The volcano's slope increases markedly with height, from 19° at its lower flanks to 35° near its summit. Like many other Aleutian volcanoes, Cleveland's flanks are especially rough up to 300 m (984 ft), covered by multiple overlapping lava flows and debris fans that form an apron around the mountain. Lava flows are always built on top of debris flows as a result of the snow melt caused by the emission of heat just before an eruption. The flows are generally short, under 1 km (0.621372736649807 mi), and thin, less than 10 m (33 ft) thick, and are somewhat vegetated. Although Mount Cleveland is the tallest mountain in the group, it is rarely completely snowed in because of its constant activity disrupts snowfall. A lack of extant erosion shows that Mount Cleveland is likely a Holocene
Holocene
The Holocene is a geological epoch which began at the end of the Pleistocene and continues to the present. The Holocene is part of the Quaternary period. Its name comes from the Greek words and , meaning "entirely recent"...
volcano, forming within the last 10,000 years. All known events have occurred at Mount Cleveland's summit vent, but there are at least five small andesite
Andesite
Andesite is an extrusive igneous, volcanic rock, of intermediate composition, with aphanitic to porphyritic texture. In a general sense, it is the intermediate type between basalt and dacite. The mineral assemblage is typically dominated by plagioclase plus pyroxene and/or hornblende. Magnetite,...
to dacite
Dacite
Dacite is an igneous, volcanic rock. It has an aphanitic to porphyritic texture and is intermediate in composition between andesite and rhyolite. The relative proportions of feldspars and quartz in dacite, and in many other volcanic rocks, are illustrated in the QAPF diagram...
volcanic domes on the lower flanks. The volcano has no caldera
Caldera
A caldera is a cauldron-like volcanic feature usually formed by the collapse of land following a volcanic eruption, such as the one at Yellowstone National Park in the US. They are sometimes confused with volcanic craters...
.
The eastern half of Chuginadak, to which Mount Cleveland is connected by a narrow isthmus
Isthmus
An isthmus is a narrow strip of land connecting two larger land areas usually with waterforms on either side.Canals are often built through isthmuses where they may be particularly advantageous to create a shortcut for marine transportation...
, consists of several low-lying volcanic cone
Volcanic cone
Volcanic cones are among the simplest volcanic formations. They are built by ejecta from a volcanic vent, piling up around the vent in the shape of a cone with a central crater. Volcanic cones are of different types, depending upon the nature and size of the fragments ejected during the eruption...
s and two prominent peaks that have been heavily eroded, partly by glaciers. Known as the Tana volcanic complex, the two features measure 1170 m (3,839 ft) and 1093 m (3,586 ft) in elevation. A sample of rhyolite
Rhyolite
This page is about a volcanic rock. For the ghost town see Rhyolite, Nevada, and for the satellite system, see Rhyolite/Aquacade.Rhyolite is an igneous, volcanic rock, of felsic composition . It may have any texture from glassy to aphanitic to porphyritic...
has been recovered from Concord Point, the easternmost point on the island.
Eruptive history
Vulcanian eruption
The term Vulcanian was first used by Giuseppe Mercalli, witnessing the 1888-1890 eruptions on the island of Vulcano. His description of the eruption style is now used all over the world for eruptions characterised by a dense cloud of ash-laden gas exploding from the crater and rising high above the...
and strombolian
Strombolian eruption
Strombolian eruptions are relatively low-level volcanic eruptions, named after the Italian volcano Stromboli, where such eruptions consist of ejection of incandescent cinder, lapilli and lava bombs to altitudes of tens to hundreds of meters...
in nature, characterized by short explosive
Explosive eruption
An explosive eruption is a volcanic term to describe a violent, explosive type of eruption. Mount St. Helens in 1980 was an example. Such an eruption is driven by gas accumulating under great pressure. Driven by hot rising magma, it interacts with ground water until the pressure increases to the...
ash clouds
Volcanic ash
Volcanic ash consists of small tephra, which are bits of pulverized rock and glass created by volcanic eruptions, less than in diameter. There are three mechanisms of volcanic ash formation: gas release under decompression causing magmatic eruptions; thermal contraction from chilling on contact...
sometimes accompanied by a'a flows, lava fountain
Lava fountain
A lava fountain is a volcanic phenomenon in which lava is forcefully but non-explosively ejected from a crater, vent, or fissure. Lava fountains may reach heights of up to . They may occur as a series of short pulses, or a continuous jet of lava. They are commonly seen in Hawaiian eruptions.-See...
s, pyroclastic flow
Pyroclastic flow
A pyroclastic flow is a fast-moving current of superheated gas and rock , which reaches speeds moving away from a volcano of up to 700 km/h . The flows normally hug the ground and travel downhill, or spread laterally under gravity...
s, ash
Volcanic ash
Volcanic ash consists of small tephra, which are bits of pulverized rock and glass created by volcanic eruptions, less than in diameter. There are three mechanisms of volcanic ash formation: gas release under decompression causing magmatic eruptions; thermal contraction from chilling on contact...
and steam
Phreatic eruption
A phreatic eruption, also called a phreatic explosion or ultravulcanian eruption, occurs when rising magma makes contact with ground or surface water. The extreme temperature of the magma causes near-instantaneous evaporation to steam, resulting in an explosion of steam, water, ash, rock, and...
emissions, lava dome
Lava dome
|250px|thumb|right|Image of the [[rhyolitic]] lava dome of [[Chaitén Volcano]] during its 2008–2009 eruption.In volcanology, a lava dome is a roughly circular mound-shaped protrusion resulting from the slow extrusion of viscous lava from a volcano...
growth, and the ejection of breadcrust bombs. Hot springs were reportedly found on the volcano in the 1800s, and persistent fumarolic activity
Fumarole
A fumarole is an opening in a planet's crust, often in the neighborhood of volcanoes, which emits steam and gases such as carbon dioxide, sulfur dioxide, hydrochloric acid, and hydrogen sulfide. The steam is created when superheated water turns to steam as its pressure drops when it emerges from...
was observed in the 1980s and 1990s. Mount Cleveland is a site of persistent steam emissions and thermal anomalies that represent constant background activity.
Little is known about Cleveland's early eruptive history as its remoteness makes it a difficult area to investigate, and discrepancies in names have caused confusion between events there and those on nearby Carlisle
Mount Carlisle
Mount Carlisle is a stratovolcano in Alaska which forms part of the 5 mile wide Carlisle Island, one of the Islands of Four Mountains which, in turn, form part of the central Aleutian Islands....
. Even today, not all possible event are confirmed as eruptions by the Alaska Volcano Observatory
Alaska Volcano Observatory
The Alaska Volcano Observatory is a joint program of the United States Geological Survey, the Geophysical Institute of the University of Alaska Fairbanks, and the State of Alaska Division of Geological and Geophysical Surveys...
, and many are listed as "possible." In observed history, Mount Cleveland may have first erupted in 1744; the first confirmed eruption occurred in 1828. The volcano erupted again in 1836 (possibly), 1893, 1897 (possibly), 1929 (possibly), 1932, and 1938 (possibly).
The first notable eruption from Mount Cleveland was a Volcanic Explosivity Index
Volcanic Explosivity Index
The Volcanic Explosivity Index was devised by Chris Newhall of the U.S. Geological Survey and Stephen Self at the University of Hawaii in 1982 to provide a relative measure of the explosiveness of volcanic eruptions....
(VEI) 3 Vulcanian eruption
Vulcanian eruption
The term Vulcanian was first used by Giuseppe Mercalli, witnessing the 1888-1890 eruptions on the island of Vulcano. His description of the eruption style is now used all over the world for eruptions characterised by a dense cloud of ash-laden gas exploding from the crater and rising high above the...
that occurred between June 10 and June 13, 1944. Lava flows extended 5 kilometres (3 mi) from the summit, and an ash plume 6000 m (19,685 ft) high was produced. Large boulders were reportedly ejected and carried out to sea by eruptive force. The eruption had the distinction of being the only confirmed direct volcanic fatality in Alaska; a small detachment from the Eleventh Air Force
Eleventh Air Force
The Eleventh Air Force is a numbered air force of the United States Air Force Pacific Air Forces . It is headquartered at Elmendorf Air Force Base, Alaska....
was stationed on the volcano at the time, and one Sergeant Purchase left his post early in the eruption to take a walk and never returned, probably killed by mudslides. At approximately 10:20, a boat sent to search for Purchase witnessed the end of the eruption. The island was abandoned for the remainder of the war.
Mount Cleveland erupted more recently in 1951, 1953, 1954 (possibly), 1975 (possibly), 1984 through 1987, 1989, 1994, and 1997. The volcano has received more focused attention in recent times due to its increased activity: it erupted in 2001, 2005, three times in 2006, 2007, three times in 2009, and twice in 2010. Of these, the most significant eruption was the 2001 eruption, which produced a 12 km (7 mi) high ash plume. This plume dispersed 120 to 150 km (74.6 to 93.2 mi) across Alaska, an unusual distance that allowed detailed satellite observations to be made. Nikolski and the surrounding region was the site of several hours of ashfall, represented in satellite imagery as areas of discolored snow. This eruption significantly disrupted air traffic in the area. The volcano has erupted at least 21 times in the last 230 years, with the most recent beginning on May 30 2010 and ending in late May or early June.
Monitoring
Alaska Volcano Observatory
The Alaska Volcano Observatory is a joint program of the United States Geological Survey, the Geophysical Institute of the University of Alaska Fairbanks, and the State of Alaska Division of Geological and Geophysical Surveys...
monitors activity at Mount Cleveland using satellite imagery. Cloud cover often obscures the volcano, which makes many events difficult to follow. In addition, the low resolution of the satellite imagery allows minor events, which do not make an impression on the satellite picture, to pass unnoticed. There are no seismic or geophysical instruments on the mountain (the nearest are in Nikolski), and some eruptions are first observed by pilots flying over the volcano. A field study was conducted in late 2001, and an automatic system based on thermal anomalies was implemented following eruptive events in 2005. In recent years the Alaska Volcano Observatory has made an effort to expand volcanic coverage westward along the Aleutian Arc.
The biggest threat posed by an eruption from Mount Cleveland is its ash plume, which can damage sensitive electronic equipment on overflying planes. Many aircraft traveling over the North Pacific and over the Arctic come within the vicinity of such a plume; the only way to avoid damage is to reroute the flight, which delays arrival time and adds $5,500 to $6,000 in extra fuel costs. Cleveland has therefore been assessed by the United States Geological Survey
United States Geological Survey
The United States Geological Survey is a scientific agency of the United States government. The scientists of the USGS study the landscape of the United States, its natural resources, and the natural hazards that threaten it. The organization has four major science disciplines, concerning biology,...
as a volcano with "[a] high aviation threat score and no real-time ground based monitoring at the present time".
2011 eruption
Satellite imagery reviewed in late July 2011 indicated thermal anomalies consistent with a new eruption of Mount Cleveland, which probably began on July 19th. A 40 metres (131.2 ft) lava dome has also been observed.The current activity is not generating an ash plume, and the surrounding land is uninhabited, so the eruption is unlikely to affect anyone. The lava dome is currently limited to the volcanic crater, but this volcano's history suggests it could produce a small flow or even an explosion that would push ash up to flight levels for a short time.
See also
- List of volcanoes in Alaska
- Aleutians West Census Area, AlaskaAleutians West Census Area, AlaskaAleutians West Census Area is a census area located in the U.S. state of Alaska. It contains most of the Aleutian Islands, from Attu Island in the west to Unalaska Island in the east, as well as the Pribilof Islands, which lie north of the Aleutians in the Bering Sea. As of 2010, the population is...
External links
- Cleveland eruption updates. Alaska Volcano ObservatoryAlaska Volcano ObservatoryThe Alaska Volcano Observatory is a joint program of the United States Geological Survey, the Geophysical Institute of the University of Alaska Fairbanks, and the State of Alaska Division of Geological and Geophysical Surveys...
.